In 1967 the investigators made a census and socio-economic survey of about one-third of a population of 13,000 Mennonites in Mexico. They also copied the Mennonite church records on all families who have lived in the population since 1922. These people were selected for study because of their simple and uniform culture insulated from mass communication media and because of their apparently unrestricted fertility. Unlike some similar religious isolates, this society supports a considerable degree of economic competition. By correlational and factoring methods, the survey has yielded a rating of each farmer in several dimensions of social and economic behavior. The census and church records have yielded vital statistics including life tables. After further editing, the survey data and the vital statistics will be analyzed together in order to reveal relations of the socio-economic variables to differences in mortality and natality.